Physalin H ameliorates LPS-induced acute lung injury via KEAP1/NRF2 axis.

Physalin H (PH), a withanolide isolated from Physalisangulata L. has been reported to have anti-inflammatory effect. However, its impact on acute lung injury (ALI) remains unexplored. In this study, we observed that PH significantly alleviated inflammation in LPS-stimulated macrophages by suppressing the release of proinflammatory cytokines (TNF-α, IL-1ß, and IL-6) and down-regulating the expression of the inflammation-related genes. RNA sequencing analysis revealed a significant up-regulation of the NRF2 pathway by PH. Further investigation elucidated that PH attenuated the ubiquitination of NRF2 by impeding the interaction between NRF2 and KEAP1, thereby facilitating NRF2 nuclear translocation and up-regulating the expression of target genes. Consequently, it regulated redox system and exerted anti-inflammatory effect. Consistently, PH also significantly alleviated pathological damage and inflammation in LPS-induced ALI mice model, which could be reversed by administration of an NRF2 inhibitor. Collectively, these results suggest that PH ameliorates ALI by activating the KEAP1/NRF2 pathway. These findings provide a foundation for further development of pH as a new anti-inflammatory agent for ALI therapy.

Design, Synthesis, and Biological Evaluation for First GPX4 and CDK Dual Inhibitors.

The coexistence of ferroptosis and other modes of death has great advantages in the treatment of cancers. A series of glutathione peroxidase 4 (GPX4) and cyclin-dependent kinase (CDK) dual inhibitors were designed and synthesized, given the synergistic anticancer effect of ML162 (GPX4 inhibitor) in combination with indirubin-3'-oxime (IO) (CDK inhibitor). Compound B9 exhibited the highest potential cytotoxic activity against all four cell lines and displayed excellent inhibitory activity against GPX4 (IC50 = 542.5 ± 0.9 nM) and selective inhibition of CDK 4/6 (IC50 = 191.2 ± 8.7, 68.1 ± 1.4 nM). Mechanism research showed that B9 could simultaneously induce ferroptosis and arrest cells at the G1 phase in both MDA-MB-231 cells and HCT-116 cells. Compared with ML162 and IO, B9 showed much stronger cancer cell growth inhibition in vivo. These results proved that developing potent GPX4/CDK dual inhibitors is a promising strategy for the malignant cancer therapy.

Discovery and optimization of indirubin derivatives as novel ferroptosis inducers for the treatment of colon cancer.

Glutathione peroxidase 4 (GPX4) is an essential antioxidant enzyme that negatively regulates ferroptosis. To exploit novel GPX4 inhibitors, we designed and synthesized 32 indirubin derivatives. Compound 31 exhibited the strongest antitumor activity against HCT-116 cells (IC50 = 0.49 ± 0.02 µM). Further studies suggested that 31 could induce ferroptosis in colon cancer cells and its cytotoxic activity could be reversed by ferroptosis inhibitors. Mechanism research showed that 31 promoted the degradation of GPX4, causing the accumulation of lipid ROS to induce ferroptosis. Animal experiments also proved that 31 could inhibit the growth of colon cancer cells in vivo and reduce the expression of GPX4 in tumor tissues. These results indicated that compound 31 had potential as a novel ferroptosis inducer agent for colon cancer.

γ-Glutamyltranspeptidase-Activated Near-Infrared fluorescent probe for visualization of Drug-Induced liver injury.

Drug-induced liver injury (DILI), induced by overdose or chronic administration of drugs, has become the leading cause of acute liver failure. Therefore, an accurate diagnostic method for DILI is critical to improve treatment efficiency. The production of γ-glutamyltranspeptidase (GGT) is closely related to the progression of drug-induced hepatotoxicity. KL-Glu exhibits a prominent GGT-activated NIR fluorescence (734 nm) with a large Stokes shift (137 nm) and good sensitivity/selectivity, making it favorable for real-time detection of endogenous GGT activity. Using this probe, we evaluated the GGT up-regulation under the acetaminophen-induced liver injury model. Moreover, KL-Glu was successfully used to assess liver injury induced by the natural active ingredient triptolide and the effective amelioration upon treatment with N-acetyl cysteine (NAC) or Glutathione (GSH) in cells and in vivo by fluorescent trapping the fluctuation of GGT for the first time. Therefore, the fluorescent probe KL-Glu can be used as a potential tool to explore the function of GGT in the progression of DILI and for the early diagnosis and prognostic evaluation of DILI.

Cephalotaxine-type alkaloids from the seeds of Cephalotaxus fortunei and their cytotoxic activities.

Six new Cephalotaxus alkaloids, including five cephalotaxine-type alkaloids, and one homoerythrina-type alkaloid, along with six known analogues, were isolated from the seeds of Cephalotaxus fortunei. Their structures were elucidated by combination of spectroscopic data analyses, time-dependent density functional theory (TDDFT) ECD calculation, and single-crystal X-ray diffraction. Cephalofortine B represents the first example of C-5 epi-cephalotaxine-type alkaloid. All isolated compounds were tested for cytotoxicities against HCT-116, A375, and SK-Mel-28 cell lines. Cephalofortine E showed moderate activity against HCT-116 cell line, with an IC50 value of 7.46 ± 0.77 µM.

Fortuneicyclidins A and B, Pyrrolizidine Alkaloids with a 7-Azatetracyclo[5.4.3.0.02,8]tridecane Core, from Cephalotaxus fortunei.

Fortuneicyclidins A (1) and B (2), a pair of epimeric pyrrolizidine alkaloids containing an unprecedented 7-azatetracyclo[5.4.3.0.02,8]tridecane core, were isolated from the seeds of Cephalotaxus fortunei, along with two biogenetically relative known analogues, 3 and 4. The structures were determined by multiple spectral techniques and chemical derivatization methods. Compound 1 showed inhibitory activity against α-glucosidase.

Tubocapsenolide A targets C-terminal cysteine residues of HSP90 to exert the anti-tumor effect.

Heat shock protein 90 (HSP90) is a chaperone protein that has been shown to regulate cancer progression. As a result, HSP90 has emerged as an attractive target for cancer therapy. Tubocapsenolide A (TA) is an anti-tumor component isolated from Tubocapsicum anomalum. Although the anti-tumor activity of TA was considered to be related to HSP90, the binding site and deep anti-tumor mechanisms still need to be elucidated. In this study, we found that TA is a covalent inhibitor of HSP90, which inhibits HSP90 ATPase activity without blocking ATP binding. Further studies indicated that TA targets the C-terminal Cys521 site, which led to HSP90 partial oligomerization and hindered its anti-aggregation and refolding activity. The damage of the chaperone activity disrupted the interaction between HSP90 and its cochaperone CDC37 as well as its client proteins, thereby inducing cell cycle arrest and apoptosis. Moreover, TA was found to have therapeutic effects on the xenograft tumor model by inducing the degradation of HSP90 client proteins. Together, our results identified HSP90 as the direct target of TA for mediating the anti-tumor activity. TA could serve as a lead compound for developing novel HSP90 C-terminal covalent inhibitors with binding site different from the ATP-binding domain.

Osteosarcoma cell proliferation suppression via SHP-2-mediated inactivation of the JAK/STAT3 pathway by tubocapsenolide A.

Introduction: Previously, we have reported a withanolide-type steroid, named tubocapsenolide A (TA), which shows potent anti-proliferative activity in several cancer cell lines. However, its inhibitory effect on the Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) pathway and therapeutic potential on osteosarcoma have not been reported. Objectives: In the present study, we aimed to investigate the effect and molecular mechanism of TA in osteosarcoma. Methods: The biological functions of TA in U2OS cells were investigated using colony formation, 5-ethynyl-20-deoxyuridine (EDU) staining, and cell cycle/apoptosis assays. The interaction between TA and Src homology 2 phosphatase 2 (SHP-2) was detected by enzyme activity and validated by target-identification methods such as drug affinity responsive target stability (DARTS), cellular thermal shift assay (CETSA), and biolayer interferometry (BLI). The in vivo anti-tumor efficacy of TA was analyzed in the xenograft tumor model. Western blotting analysis was performed to detect the protein expression levels. Results: TA exhibited antitumor activity against osteosarcoma both in vitro and in vivo by regulating the JAK/STAT3 signaling pathway. Mechanically, TA interacted with SHP-2 directly and activated its phosphatase activity. Importantly, protein tyrosine phosphatase (PTP) inhibitor, SHP-2 inhibitor, and SHP-2 siRNA could reverse the inhibitory effect of TA on the JAK/STAT3 signaling pathway and restored the TA-induced cell death. Conclusion: TA activated the phosphatase activity of SHP-2, which resulted in the inhibition of the JAK/STAT3 pathway and contributed to the antitumor efficacy of TA. Collectively, these findings suggested that TA could serve as a novel therapeutic agent for the treatment of osteosarcoma.